Tibial prosthesis systems, kits, and methods

ABSTRACT

Tibial prosthesis systems for implantation or use in a knee joint are disclosed. A tibial prosthesis system can include a bearing component, a base component, a shim component, and optionally a spacer component. The shim or spacer component can be inserted between an inferior surface of the bearing component and a superior surface of the base component. The insertion of the shim or spacer component can provide spacing adjustment between the bearing and base components. The shim component can include one or both of a medial edge having a different height than a lateral edge or an anterior edge having a different height than a posterior edge. The differing edge height of the shim component can provide a surgeon with knee joint kinematic insight regarding an angled bone cut before the cut is made, and can allow for sizing of an appropriately permanent prosthesis system using a reduced number of provisional components.

CLAIM OF PRIORITY

This application claims the benefit of priority under 35 U.S.C. §119(e)of Claypool et al., U.S. Provisional Patent Application Ser. No.61/618,376, entitled “TIBIAL PROSTHESIS SYSTEMS, KITS, AND METHODS,”filed on Mar. 30, 2012, and also claims the benefit of priority under 35U.S.C. §119(e) of Claypool et al., U.S. Provisional Patent ApplicationSer. No. 61/740,268, entitled “TIBIAL PROSTHESIS SYSTEMS, KITS, ANDMETHODS,” filed on Dec. 20, 2012, each of which is herein incorporatedby reference in its entirety.

TECHNICAL FIELD

This patent document pertains generally to tibial prosthesis systems,kits, and methods.

BACKGROUND

Provisional knee prosthesis systems, including a plurality ofprovisional components, can be positioned on a distal end of a femur ora proximal end of a tibia to allow a surgeon to test and appropriatelyfit a permanent knee prosthesis system within a patient. During surgery,the surgeon can remove and replace a provisional component having afirst uniform thickness with a provisional component having a seconduniform thickness to arrive at an appropriate configuration of thepermanent knee prosthesis system.

OVERVIEW

This patent document pertains generally to provisional tibial prosthesissystems, kits, and methods, including one or more provisional tibialcomponents that can collectively be used to replicate permanent (orfinal) tibial components or mimic bone cuts believed to be necessaryduring a surgical procedure. It is believed that the provisional tibialcomponents can also be designed for, or find use as, permanent tibialcomponents. Thus, while this disclosure relates to provisional uses ofthe present tibial prosthesis systems, kits, and methods, it should beappreciated that such subject matter can also find use in permanentapplications. When used provisionally, the tibial prosthesis systems,kits, and methods disclosed herein can assist in determining a properbone cut angle to be made (e.g., to a tibia or a femur) or a size,shape, or other configuration of a permanent tibial prosthesis systemthat is designed to replace all or a portion of a knee joint. Thepresent tibial prosthesis systems, kits, and methods can be used inconjunction with one or both of a permanent tibial prosthesis system, asdisclosed in U.S. Provisional Patent Application Ser. No. 61/381,800,filed on Sep. 10, 2010 and entitled “TIBIAL PROSTHESIS FACILITATINGROTATIONAL ALIGNMENT,” or a shim handling instrument and user-interface,as disclosed in U.S. Provisional Patent Application Ser. No. 61/424,222,filed on Dec. 17, 2010 and entitled “USER INTERFACE RELATED TO ASURGICAL PROVISIONAL,” the entire disclosures of each of which arehereby expressly incorporated by reference herein.

The present inventors recognize, among other things, that existingprovisional systems, kits, and methods fail to provide a surgeon withinsight of knee joint kinematics if an angled bone cut (e.g., a bone cutthat is not parallel to a joint line of the knee) is made to a proximalend of the tibia or a distal end of the femur. The present inventorsfurther recognize that existing provisional systems, kits, and methodsrequire the stacking of a high number of provisional components toarrive at an appropriate configuration of the permanent tibialprosthesis system or fail to provide sensed force or pressure dataproviding a real-time indication of provisional knee joint balance.

The present shim components, which can include one or both of a medialedge having a different height than a lateral edge or an anterior edgehaving a different height than a posterior edge, advantageously providea surgeon with knee joint kinematic insight regarding an angled bone cutbefore the cut is made and can reduce the number of provisionalcomponents needed for permanent system sizing. The present shimcomponents can provide the surgeon with the ability to appropriatelyconfigure the tibia, the femur, and/or the permanent tibial prosthesissystem to counterbalance a deficiency (e.g., varus, valgus,anterior/posterior, or posterior/anterior sloping) of the knee jointbefore making certain angled bone cuts and using a reduced number ofprovisional components.

A tibial prosthesis system can include a provisional bearing component,a bearing support component, such as a base or plate component, and theprovisional shim component. The shim component can be inserted betweenan inferior surface of the bearing component and a superior surface ofthe bearing support component. The insertion of the shim componentprovides spacing adjustment between the bearing and bearing supportcomponents. A sensor can be coupled to or integrated with the bearing,bearing support, or shim components for real-time knee joint balancetesting.

To further illustrate the tibial prosthesis systems and kits disclosedherein, a non-limiting list of examples is provided here:

In Example 1, a tibial prosthesis system can comprise a bearingcomponent, a base component, and a shim component. The bearing componentcan have a superior articulating surface and an inferior surface. Thebase component can have a superior surface and an inferior surface. Theshim component can be configured to be slidable between the inferiorsurface of the bearing component and the superior surface of the basecomponent in an anterior/posterior direction. The shim component caninclude one or both of a medial edge having a different height than alateral edge or an anterior edge having a different height than aposterior edge.

In Example 2, the tibial prosthesis system of Example 1 can optionallybe configured such that an inferior surface of the shim componentincludes a medial to lateral angle of between +3 degrees and −3 degrees,inclusive, or an anterior to posterior angle of between +3 degrees and−3 degrees, inclusive.

In Example 3, the tibial prosthesis system of any one or any combinationof Examples 1 or 2 can optionally be configured such that the inferiorsurface of the bearing component includes a slot, and a superior surfaceof the shim component includes a rail configured to slidably engage theslot in the anterior/posterior direction.

In Example 4, the tibial prosthesis system of any one or any combinationof Examples 1-3 can optionally be configured such that the basecomponent includes a first component, having a superior surface and aninferior surface, and a second component configured to receive andengage the inferior surface of the first component.

In Example 5, the tibial prosthesis system of Example 4 can optionallybe configured such that the first component includes at least one rampedsurface extending between its inferior surface and superior surface. Theat least one ramped surface can be configured to engage an undercut ofthe second component. A projection extending from the inferior surfaceof the first component can be configured to engage with a cavity of thesecond component.

In Example 6, the tibial prosthesis system of Example 4 can optionallybe configured such that the second component is one of a sizing platecomponent, a provisional plate component, or a permanent platecomponent.

In Example 7, the tibial prosthesis system of any one or any combinationof Examples 1-6 can optionally be configured such that the differentheight of the medial and lateral edges or of the anterior and posterioredges is measured in a proximal/distal direction.

In Example 8, the tibial prosthesis system of any one or any combinationof Examples 1-7 can optionally be configured such that the shimcomponent is configured to secure a position of the bearing componentand the base component relative to each other.

In Example 9, the tibial prosthesis system of any one or any combinationof Examples 1-8 can optionally be configured such that the superiorsurface of the base component includes a projection configured to atleast partially engage within a cavity of the inferior surface of thebearing component.

In Example 10, the tibial prosthesis system of Example 9 can optionallybe configured such that the engagement of the projection of the basecomponent at least partially within the cavity of the bearing componentis configured to inhibit at least one of relative anterior/posteriormovement or relative medial/lateral movement between the base andbearing components.

In Example 11, the tibial prosthesis system of any one or anycombination of Examples 1-10 can optionally further comprise one or moresensors coupled to or integrated with at least one of the bearingcomponent, the base component, or the shim component.

In Example 12, the tibial prosthesis system of Example 11 can optionallybe configured such that the one or more sensors include a plurality ofsensors coupled to or integrated with the bearing component.

In Example 13, the tibial prosthesis system of Example 12 can optionallybe configured such that the plurality of sensors is positioned betweenthe superior articulating surface and the inferior surface of thebearing component.

In Example 14, a tibial prosthesis kit can comprise a set of differentsized shim components. At least one of the shim components can includeone or both of a medial edge having a different height than a lateraledge or an anterior edge having a different height than a posterioredge.

In Example 15, the tibial prosthesis kit of Example 14 can optionally beconfigured such that an inferior surface of at least one shim component,from the set of different sized shim components, includes a medial tolateral angle of between +3 degrees and −3 degrees, inclusive, or ananterior to posterior angle of between +3 degrees and −3 degrees,inclusive, relative to horizontal.

In Example 16, the tibial prosthesis kit of any one or any combinationof Examples 14 or 15 can optionally further comprise instructions forinserting at least one shim component, from the set of different sizedshim components, between a bearing component and a base component.

In Example 17, the tibial prosthesis kit of Example 16 can optionally beconfigured such that the set of different sized shim components providebetween 10 mm and 20 mm, inclusive, of spacing adjustment between aportion of the bearing component and a portion of the base component.

In Example 18, the tibial prosthesis kit of any one or any combinationof Examples 14-17 can optionally further comprise one or more sensorsintegrated with the shim component.

In Example 19, the tibial prosthesis kit of any one or any combinationof Examples 14-18 can optionally further comprise a set of differentsized base components.

In Example 20, the tibial prosthesis kit of any one or any combinationof Examples 14-19 can optionally further comprise a shim handlinginstrument including an interface configured to engage with a front endportion of each of the set of different sized shim components.

In Example 21, a tibial prosthesis system can comprise a bearingcomponent, a base component, a spacer component, and one or more shimcomponents. The bearing component can have a superior articulatingsurface and an inferior surface. The base component can have a superiorsurface and an inferior surface. The spacer component can be configuredto be slidable between the inferior surface of the bearing component andthe superior surface of the base component in an anterior/posteriordirection. The one or more shim components can be configured to beslidable between the inferior surface of the bearing component and thesuperior surface of the base component. At least one of the shimcomponents can include one or both of a medial edge having a differentheight than a lateral edge or an anterior edge having a different heightthan a posterior edge.

In Example 22, the tibial prosthesis system of Example 21 can optionallybe configured such that the one or more shim components include a firstshim and a second shim.

In Example 23, the tibial prosthesis system of any one or anycombination of Examples 21 or 22 can optionally be configured such thatthe bearing component includes a post extending from the superiorarticulating surface.

In Example 24, the tibial prosthesis system of any one or anycombination of Examples 21-23 can optionally further comprise a screwconfigured to extend partially through each of the bearing component andthe base component, in a distal direction from the superior articulatingsurface, to attach the bearing component to the base component.

In Example 25, the tibial prosthesis system of Example 24 can optionallybe configured such that the spacer component and the shim component areconfigured to be slidable between the inferior surface of the bearingcomponent and the superior surface of the base component when the screwattaches the bearing component to the base component.

In Example 26, the tibial prosthesis system of any one or anycombination of Examples 21-25 can optionally be configured such that thespacer is removable from the tibial prosthesis system prior to slidingthe one or more shim components between the inferior surface of thebearing component and the superior surface of the base component.

In Example 27, the tibial prosthesis system of any one or anycombination of Examples 1-26 can optionally be configured such that allelements or options recited are available to use or select from.

These and other examples and features of the present tibial prosthesissystems or kits will be set forth in part in the following DetailedDescription. This Overview is intended to provide non-limiting examplesof the present subject matter—it is not intended to provide an exclusiveor exhaustive explanation. The Detailed Description below is included toprovide further information about the present tibial prosthesis systems,kits, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like numerals can be used to describe similar elementsthroughout the several views. Like numerals having different lettersuffixes can be used to represent different views or features of similarelements. The drawings illustrate generally, by way of example, but notby way of limitation, various embodiments discussed in the presentdocument.

FIGS. 1-2 illustrate knee joint structures providing suitableenvironments in which a tibial prosthesis system, as constructed inaccordance with at least one embodiment, can be used.

FIG. 3 illustrates a partially resected knee joint structure and atibial prosthesis system, as constructed in accordance with at least oneembodiment.

FIGS. 4A-4B respectively illustrate assembled and component views of atibial prosthesis system, as constructed in accordance with at least oneembodiment.

FIG. 5 illustrates a method of using a tibial prosthesis system, asconstructed in accordance with at least one embodiment.

FIG. 6A-6B respectively illustrate assembled and component views of atibial prosthesis system and a shim handling instrument, as constructedin accordance with at least one embodiment.

FIGS. 7-8 illustrate front views of a shim component of a tibialprosthesis system, as constructed in accordance with at least twoembodiments.

FIGS. 9-10 illustrate side views of a shim component of a tibialprosthesis system, as constructed in accordance with at least twoembodiments.

FIGS. 11-12B illustrate exploded views of a base component and a platecomponent of a tibial prosthesis system, as constructed in accordancewith at least one embodiment.

FIGS. 13-14 illustrate perspective views of portions of a tibialprosthesis system, as constructed in accordance with at least oneembodiment.

FIGS. 15A-15D illustrate various perspective views of a bearingcomponent, as constructed in accordance with at least one embodiment.

FIGS. 16A-16B illustrate superior and inferior sides, respectively, of abase component, as constructed in accordance with at least oneembodiment.

FIG. 17 illustrates a perspective view of a spacer component, asconstructed in accordance with at least one embodiment.

FIG. 18 illustrates a perspective view of a shim component, asconstructed in accordance with at least one embodiment.

FIGS. 19-20 illustrate perspective views of a spacer component, asconstructed in accordance with at least one embodiment.

FIG. 21 illustrates a perspective view of a spacer component positionedin a tibial prosthesis system, as constructed in accordance with atleast one embodiment.

FIG. 22 illustrates a perspective view of a provisional or trialprosthesis system, as constructed in accordance with at least oneembodiment.

FIGS. 23A-23B illustrate assembled and component views, respectively, ofa bearing component, as constructed in accordance with at least oneembodiment.

FIG. 24 illustrates a top surface of a bearing component sensor plate,as constructed in accordance with at least one embodiment.

FIG. 25 illustrates a frame and a non-articulating side of a bearingcomponent top portion, as constructed in accordance with at least oneembodiment.

FIGS. 26A-27C illustrate one or more components of a provisional tibialprosthesis system in use with a handling instrument, as constructed inaccordance with at least one embodiment.

FIG. 28 illustrates a plurality of templates for determining a propertibial tray size prior to selecting a tibial prosthesis system, asconstructed in accordance with at least one embodiment.

FIG. 29 illustrates an example of a kit that can include a userinterface, a handling instrument, and a plurality of components of atrial prosthesis system, as constructed in accordance with at least oneembodiment.

FIGS. 30-34 illustrate digital images that can be generated anddisplayed on a user interface, as constructed in accordance with atleast one embodiment.

DETAILED DESCRIPTION

The present inventors recognize that it can be desirable to providesurgeons with knee joint kinematic insight before certain bone cuts aremade (e.g., to a tibia or a femur) and with the ability to quicklycreate a configuration appropriate for a permanent tibial prosthesissystem using provisional components. The present tibial prosthesissystems, kits, and methods can include a provisional bearing component,a bearing support component, such as a base component or a platecomponent, and a provisional shim component. The shim component caninclude one or both of a medial edge having a different height than alateral edge or an anterior edge having a different height than aposterior edge and can be inserted between the bearing component and thebearing support component. The differing height profile of the shimcomponent can provide a surgeon with knee joint kinematic insightregarding an angled bone cut before the cut is made and can allow forsizing of an appropriate permanent prosthesis component configurationusing a reduced number of provisional components. A sensor can becoupled to or integrated with the bearing, bearing support, or shimcomponents for real-time knee joint balance testing.

To better understand knee joint replacement procedures, it can behelpful to understand the relationship of bones and bone cuts that canbe made to orient various provisional and permanent prosthesiscomponents within a knee joint. FIGS. 1 and 2 illustrate severalfeatures of knee joint structures and orientations. In FIG. 1, a frontalview of a lower limb 102, including a femur 104 and a tibia 106, isshown to illustrate various lower limb axes. The femur 104 has ananatomic axis 108 that coincides generally with its intramedullarycanal. The femur 104 also has a mechanical axis 110, or load axis,running from the center of a femoral head 112 to the center of a kneejoint 114. The angle 116 extending between these two axes varies amongthe patient population, but is generally on the order of between 5-7degrees, inclusive. Like the femur 104, the tibia 106 also has ananatomic axis coinciding generally with its intramedullary canal. Themechanical axis 118 of the tibia 106 runs from the center of the kneejoint 114 to the center of an ankle region 120 and is generallycollinear with its anatomic axis.

A joint line 122, about which the knee joint 114 flexes, isapproximately parallel to a line through medial and lateral femoralcondyles 124 and to a tibial plateau 126. Although illustrated asperpendicular in FIG. 1, the joint line 122 can extend at a varus orvalgus angle relative to the mechanical axes 110 and 118 of the femur104 and tibia 106, respectively. Normally, during a partial or totalknee replacement procedure, portions of a distal end of the femur 104 ora proximal end of the tibia 106 are resected to be parallel orapproximately parallel to the joint line 122, and thus perpendicular tothe mechanical axes 110 and 118, as indicated at 128 and 130,respectively.

FIG. 2 illustrates a closer view of the knee joint 114 and itscoordinate system, in which a medial/lateral axis 202 correspondsapproximately to the joint line 122 (FIG. 1), a proximal/distal axis 204corresponds approximately to the mechanical axes 110 and 118 (FIG. 1),and an anterior/posterior axis 206 is approximately normal to the othertwo axes. Position along each of these axes can be depicted by arrows,which can represent the medial/lateral 208, anterior/posterior 210, andproximal/distal 212 positioning of inserted prosthesis components.Rotation about each of these axes can also be depicted by arrows.Rotation about the proximal/distal axis 204 can correspond anatomicallyto external rotation of a femoral component, while rotation about theanterior/posterior axis 206 and medial/lateral axis 202 can correspondto extension plane slope and varus/valgus angle of a component,respectively. Depending on a position of the proximal tibial cut 130(FIG. 1) made, a varus/valgus angle 214, extension plane angle 216,external rotation 218, or joint extension gap can be affected.Similarly, a position of the distal femoral cut 128 (FIG. 1) can affectthe location of the joint line 122, the extension gap, the varus/valgusangle 214, or the extension plane angle 216.

FIG. 3 illustrates a partially resected knee joint 314 structure,including a proximal tibial cut 130, and a provisional tibial prosthesissystem 340. The provisional tibial prosthesis system 340 can include abearing component 342, a base component 344, a plate component 350, anda shim component 346 insertable between an inferior surface 348 of thebearing component 342 and a superior surface 352 of the base component344. The shim component 346 can include one or both of a medial edgehaving a different height than a lateral edge or an anterior edge havinga different height than a posterior edge and can be used as a heightvarying spacer block between the bearing component 342 and the basecomponent 344. The spacing of the bearing component 342 from the basecomponent 344, for example, is adjustable to allow for representation ofa variety of different sized angled bone cuts that can be made to afemur 104 or a tibia 106 or permanent tibial prosthesis systems. Theshim component 346 can be inserted between the inferior surface 348 ofthe bearing component 342 and the superior surface 352 of the basecomponent 344 using a shim handling instrument 354. The shim handlinginstrument 354 can include a release means 356 to disengage the shimcomponent 346 after its insertion between the bearing 342 and base 344components.

FIGS. 4A and 4B respectively illustrate assembled and component views ofa provisional tibial prosthesis system 340. The provisional tibialprosthesis system 340, or components thereof, can be used to mimicgeometry of one or both of an angle bone cut to be made or a permanenttibial prosthesis system. For example, the assembled tibial prosthesissystem 340 of FIG. 4A, illustrates a bearing component 342, a shimcomponent 346, a base component 344, and a plate component 350. A stemcomponent 358 can be attached to the plate component 350 and used tosecure the plate component 350 to a resected tibia 106 (FIG. 3).

Each component of the provisional tibial prosthesis system 340 includesan associated height. A shim component height 347 can be combined with abearing component height 343 and a base component height 345, forexample, to represent a desired height of a permanent tibial prosthesissystem. A plurality of different or varying sized shims 346 can beslidably inserted between the bearing component 342 and a bearingsupport component, such as the base component 344, in ananterior/posterior 210 direction. Advantageously, the different orvarying sized shims 346 can be inserted and removed without removing thebearing component 342 or the bearing support component from within aknee joint 314 (FIG. 3). Instead, all that is needed is a distraction ofthe knee joint 314 in an amount equal or approximately equal to theheight profile of a particular shim component 346. In one example, theshim handling instrument 354 can be used to engage one or more handlingalignment voids of a shim component 346 to assist in inserting andremoving the shim component 346 between the bearing component 342 andthe bearing support component 344. The one or more handling alignmentvoids of the shim component 346 can be consistent over the broad rangeof different sized shim components for universal compatibility with theshim handling instrument 354.

Each component of the provisional tibial prosthesis system 340 caninclude a structure defined by various surfaces, voids, or cavities. Asshown in FIG. 4B, the bearing component 342, for example, can include aninferior surface 348, an opposing superior surface 460, and a peripheralwall 462 extending from the inferior surface 348 to the superior surface460. The bearing component 342 can further include an anterior side 464,a posterior side 466, a lateral side 468, and a medial side 470. Thesuperior surface 460 can be configured to articulate with natural orprosthetic condyles of a distal femur and can include a bearing lateralarticular surface portion and a bearing medial articular surfaceportion, with a central tibial eminence 472 disposed between thearticular surface portions. The inferior surface 348 can include abearing cavity and one or more bearing nub cavities. The bearing cavitycan extend from the inferior surface 348 toward the superior surface 460and can be sized and shaped to accept a projection of the base component344. The bearing nub cavities can extend on opposing sides of thebearing cavity and can each be sized and shaped to receive a nub locatedon the projection of the base component 344.

A posterior cruciate ligament (PCL) cutout 474 can be disposed at theposterior side 466 between the articular surfaces. The PCL cutout 474can be sized and positioned to correspond with a PCL of the knee joint314. In the example of FIG. 4B, the bearing component 342 is illustratedas a cruciate retaining bearing component, although it is contemplatedthat other tibial bearing components can be used. Bearing componentsthat cooperate to form a posterior stabilized prosthesis, as shown inthe example of FIG. 4A, or a knee prosthesis having an intermediatelevel of constraint between a posterior stabilized and cruciateretaining prosthesis are within the scope of the present disclosure. Thebearing component 342 can also be made available in a variety of shapesand sizes to accommodate a variety of patient knee joints.

The base component 344 can include an inferior surface 476, an opposingsuperior surface 352, and a peripheral wall 480 extending from theinferior surface 476 to the superior surface 352. The base component 344can further include an anterior side 481, a posterior side 482, alateral side 484, and a medial side 486. A projection 488, including oneor more nubs 490, can extend from the superior surface 352. Theprojection 488 and nubs 490 can be configured to be received within, andcouple to, the bearing and bearing nub cavities of the bearing component342. The base component 344 can include one or more of a W-shaped notch492 at the posterior side 482, an undercut portion to mate with a raisedperimeter of the plate component 350, a medial side groove, and alateral side groove.

The bearing component 342 and the base component 344 can be coupled toor engaged with each other. In an example, the bearing component 342 canbe positioned atop of the base component 344 and the projection 488,including the one or more nubs 490, of the base component 344 can bepositioned within the bearing and bearing nub cavities of the bearingcomponent 342. The base component 344 can be secured to the bearingcomponent 342 in a medial/lateral direction 208 (FIG. 2) when theprojection 488 is received with the bearing cavity and can be secured inan anterior/posterior direction 210 (FIG. 2) when the one or more nubs490 are received with respective nub cavities. The walls of the bearingcavity can provide a physical barrier to inhibit significant relativemovement between the base component 344 and the bearing component 342 inthe medial/lateral direction 208. Similarly, the walls of the bearingnub cavities can provide a physical barrier to inhibit significantrelative movement between the base component 344 and the bearingcomponent 342 in the anterior/posterior direction 210. When the bearingcomponent 342 is positioned atop the base component 344, and beforeinsertion of the shim component 346, the bearing component can 342 bemovable relative to the base component 344 in a proximal/distaldirection 212 (FIG. 2).

As further discussed with respect to and illustrated in FIGS. 11 and 12,below, the base component 344 can be secured to the base plate 350, suchthat the base component 344 is located between the bearing component 342and the base plate 350.

Turning again to FIG. 4B, the shim component 346 can include an inferiorsurface 461, an opposing superior surface 463, and a peripheral wall 465extending from the inferior surface 461 to the superior surface 463. Theperipheral wall 465 can define an exterior profile of the shim component346. In an example, the exterior profile of the shim component 346 cansubstantially match an exterior profile of the base component 344 or theplate component 350. The shim component 346 can further include ananterior side 467, a posterior side 469, a lateral side 471, and amedial side 473.

The superior surface 463 can include one or more rails 475 and one ormore handling alignment voids 477. The one or more rails 475 can beconfigured to slidably engage one or more slots on the inferior surface348 of the bearing component 342. The rails 475 can extend from theanterior side 467 toward the posterior side 469, such in an orientationparallel to the anterior/posterior direction 210. The rails 475 caninclude lead-in edges 479 to facilitate alignment and engagement withthe slots of the bearing component 342. The rail 475/slot engagementbetween the shim component 346 and the bearing component 342 can inhibitlift-off the bearing component 342 from the shim component 346. The oneor more handling alignment voids 477 can be configured to engage with aninterface of a shim handling instrument, such as is shown in FIG. 6A.

A set of different sized shim components 346 can be provided in a kit toallow for varying levels of adjustment of the provisional tibialprosthesis system 340 and insight into knee joint kinematics if certainbone cuts are made to a tibia 106 (FIG. 1) or a femur 104 (FIG. 1).Particularly, the distance between the bearing component 342 and thebase component 344 can be increased or decreased by inserting andremoving different sized shim components 346. At least one of the shimcomponents 346 can include one or both of a medial edge having adifferent height than a lateral edge or an anterior edge having adifferent height than a posterior edge. The medial edge height and thelateral edge height can be sized such that the inferior surface 461 ofthe shim component 346 includes a medial to lateral angle of between +3degrees and −3 degrees, inclusive. The anterior edge height and theposterior edge height can be sized such that the inferior surface 461 ofthe shim component 346 includes an anterior to posterior angle ofbetween +3 degrees and −3 degrees, inclusive. Two or more shimcomponents 346 from the set can, in an example, be stacked to achievedesirable knee joint kinematics. It is believed that the set ofdifferent sized shim components 346 can include any desired number ofshims having a constant or differing height.

FIG. 5 illustrates a method 500 of using a provisional tibial prosthesissystem to determine a proper angle of a bone cut to be made, if any, andan appropriate size (e.g., height) for a permanent tibial prosthesissystem in a knee joint. At 502, a surgeon or other caregiver selects aparticular size of the provisional tibial prosthesis system believed tobe suitable for a patient. The provisional tibial prosthesis system caninclude a bearing member, a bearing support component, comprising one orboth of a base component or a plate component, and a shim component. Theplate component can include an inferior surface configured to contact aresected portion of a tibia and an opposing superior surface. The basecomponent can include a base component height and be attachable to theplate component. The bearing component can include a bearing componentheight, and the shim component can include a shim component height. Theshim component can be configured to be slidably received between thebearing component and the bearing support component in ananterior/posterior direction.

At 504, a proximal end portion of the patient's tibia is resected to beparallel or approximately parallel to a joint line of a knee. The tibiacan be resected using standard surgical techniques to provide asubstantially flat surface for receipt of the inferior, bone contactingsurface of the plate component. Once the proximal end portion of thetibia is resected, the plate component can be implanted and secured tothe resected tibia, at 506.

At 508, one or more of the selected bearing, shim, and base componentscan be positioned atop the plate component. In an example, the selectedbearing and base components can initially be positioned atop the platecomponent, and subsequently, the selected shim component can be insertedbetween the bearing and base components in the anterior/posteriordirection. The inserted shim component can include one or both of amedial edge having a different height than a lateral edge or an anterioredge having a different height than a posterior edge to counterbalance adeficiency (e.g., varus, valgus, anterior/posterior, orposterior/anterior sloping) of the knee joint.

At 510, the surgeon can perform one or more of a stability, a forcebalance, or a range of motion test of the knee joint to determinewhether proper joint kinematics are present. The testing can includesensing at least one of a pressure, force, or position of the knee jointusing a sensor coupled to or integrated with a provisional component. Ifthe surgeon determines that proper knee joint kinematics is present,sizing procedures can begin, at 516. The sizing procedures can includedetermining whether an angled bone cut to the tibia and/or femur (e.g.,a bone cut that is not parallel to the joint line of the knee) isneeded, at 517, such as to counterbalance the knee joint deficiency, ordetermine the height of the provisional tibial prosthesis system. Theangled bone cut to the tibia and/or femur can correspond to a heightprofile of the selected shim. The sizing procedures can use a sizingguide including alignment pins that fit in respective exterior voids inone or more provisional components to properly align the sizing guide tothe components. Once properly aligned, a locking component of the sizingguide can slide along a shim ramp, for example, and, when the lockingcomponent slides past the shim ramp, a biasing force on the lockingcomponent can cause the locking component to travel downward and engagea backside of shim ramp to lock the sizing guide to the shim component.

At 512, if the provisional tibial prosthesis system is determined to notbe properly sized due to improper joint kinematics being present, anadditional or different sized shim component can be selected. At 514,the originally selected shim component can be removed from between thebearing component and the bearing support component and/or the newlyselected shim component can be inserted between the bearing componentand the bearing support component. The newly selected shim component caninclude at least one of a medial edge, a lateral edge, an anterior edge,or a posterior edge having a different height than the originallyselected shim component. Insertion and removal of the shim componentscan be achieved in the anterior/posterior direction using a shimhandling instrument. The bearing and bearing support components can beconfigured and coupled to each other in such a way that removal orinsertion of shim components does not disturb the coupling arrangement.

With the newly selected shim component in place, the surgeon can againperform one or more of a stability, a force balance, or a range ofmotion test of the knee joint, at 510, to determine whether proper jointkinematics are present. Shim component replacement or stacking can berepeated, using a variety of different or similarly sized shims and avariety of different numbers of shims, until the surgeon determines thatproper joint kinematics are present.

Finally, at 518, a permanent tibial prosthesis system can be selectedand implanted. The permanent tibial prosthesis system can include aheight that corresponds to the height of one or more provisional tibialprosthesis system components.

FIGS. 6A and 6B respectively illustrate assembled and component views ofa provisional tibial prosthesis system 340 and a shim handlinginstrument 354 attachable to a shim component 346 of the system. Asdiscussed with respect to FIG. 5, above, the shim handling instrument354 can be used for insertion or removal of different sized shimcomponents 346. The shim handling instrument 354 can include, amongother things, a handle body 602, a user-engageable end 604, an opposingattachment end 606, one or more alignment pins 608, release means 356(e.g., a release button), and an engageable tooth 610. The one or morealignment pins 608 can be positioned on each side of the engageabletooth 610. The alignment pins 608 can be configured to fit intorespective handling alignment voids 477 positioned near an anterior side467 of the shim component 346.

When the shim handling instrument 354 and the shim component 346 areproperly aligned, the engageable tooth 610 can be configured to slidealong a shim ramp 612. When the engageable tooth 610 slides along theshim ramp 612, a biasing force on the engageable tooth 610 can cause thetooth to travel downward and engage a backside of the shim ramp 612,thereby locking the shim handling instrument 354 to the shim component346. The biasing force can be exerted on the engageable tooth 610 by atension spring.

When the shim handling instrument 354 is locked to the shim component346, a surgeon holding the user-engageable end 604 of the shim handlinginstrument 354 can insert the shim component 346 between a bearingcomponent 342 and a bearing support component, such as one or both of abase component 344 or a plate component 350, in an anterior/posteriordirection 210 (FIG. 2). The insertion of the shim component 346 canspace the bearing component 342 from the bearing support component adistance equal to the shim component height 347 (FIG. 4A) along aproximal/distal axis 204 (FIG. 2). During insertion of the shimcomponent 346, an entry ramp 614 on a posterior side 469 of the shimcomponent 346 can be used to urge, in a ramp-like manner, separation ofthe bearing component 342 and the bearing support component. Once theshim component 346 is fully inserted between the bearing component 342and the bearing support component, the release means 356 can bedepressed to overcome the downward biasing force on the engageable tooth610. In this way, the engageable tooth 610 can be disengaged from thebackside of the shim ramp 612 and the shim handling instrument 354 canbe disengaged from the shim component 346. In a similar manner, the shimhandling instrument 354 can be used to remove the shim component 346from between the bearing component 342 and the bearing supportcomponent.

Advantageously, the present provisional tibial prosthesis system 340 canbe adjusted in a manner requiring a knee joint 114 (FIG. 2) to only bedistracted by a distance equal to a height profile of the shim component346. The shim components 346, as shown in FIGS. 8 and 10, can includeone or both of a medial edge having a different height than a lateraledge or an anterior edge having a different height than a posterioredge. Differing height shim components 346 can advantageously provide asurgeon with joint kinematic insight regarding an angled bone cut beforethe cut is made, and can reduce the number of provisional componentsneeded during surgery sizing by offering tailored separation betweenknee joint components. Also, the bearing component 342 and the bearingsupport component, such as the base component 344, do not have to beremoved from the knee joint 114 to insert and remove shim components346.

FIGS. 7 and 8 illustrate front views of at least two versions of a shimcomponent of a provisional tibial prosthesis system. The shim component346A of FIG. 7 includes a medial edge height 702 that is the same orsubstantially the same as a lateral edge height 704. In contrast, theshim component 346B of FIG. 8 includes a medial edge height 702 that isdifferent than a lateral edge height 704. In the example shown, themedial edge height 702 is greater than the lateral edge height 704 andcan be used by a surgeon to analyze possible bone cuts for a patientexperiencing a varus (or bow-legged) knee joint. Alternatively, themedial edge height 702 can be less than the lateral edge height 704 andcan be used by a surgeon to analyze possible bone cuts for a patientexperiencing a valgus (for knock-kneed) joint. Due to a heightdifference between the medial and lateral edges, an inferior surface 461of the shim component can include a medial to lateral angle of between+3 degrees and −3 degrees, inclusive. The wedge-like shape of the shimcomponent 346B can be used by the surgeon to assess kinematics of a kneejoint if a particular bone cut is made. In this way, the wedge-likeshape can be used as a feedback mechanism.

In some examples, the medial edge height 702 or the lateral edge height704 can provide between 10 mm and 20 mm, inclusive, of spacingadjustment between a bearing component 342 (FIG. 4A) and a bearingsupport component, such as a base component 344 (FIG. 4A) or a platecomponent 350 (FIG. 4A). In some examples, the medial edge height 702 orthe lateral edge height 704 can provide between 10 mm and 14 mm,inclusive, of spacing adjustment and an additional 0 mm to 6 mm ofspacing adjustment can be provided by different sizes of the bearingsupport component.

FIGS. 9 and 10 illustrate side views of at least two versions of a shimcomponent of a tibial prosthesis system. The shim component 346C of FIG.9 includes an anterior edge height 706 that is the same or substantiallythe same as a posterior edge height 708. In contrast, the shim component346D of FIG. 10 includes an anterior edge height 706 that is differentthan a posterior edge height 708. In the example shown, the anterioredge height 706 is less than the posterior edge height 708 and can beused by a surgeon to analyze possible bone cuts for a patientexperiencing an anterior to posterior sloped knee joint. Alternatively,the anterior edge height 706 can be greater than the posterior edgeheight 708 and can be used by a surgeon to analyze possible bone cutsfor a patient experiencing a poster to anterior sloped knee joint. Dueto a height difference between the anterior and posterior edges, aninferior surface 461 of the shim component can include an anterior toposterior angle of between +3 degrees and −3 degrees, inclusive. Thewedge-like shape of the shim component 346D can be used by the surgeonto assess kinematics of a knee joint if a particular bone cut is made.In this way, the wedge-like shape can be used as a feedback mechanism.

In some examples, the anterior edge height 706 or the posterior edgeheight 708 can provide between 10 mm and 20 mm, inclusive, of spacingadjustment between a bearing component 342 (FIG. 4A) and a bearingsupport component, such as a base component 344 (FIG. 4A) or a platecomponent 350 (FIG. 4A). In some examples, the anterior edge height 706or the posterior edge height 708 can provide between 10 mm and 14 mm,inclusive, of spacing adjustment and an additional 0 mm to 6 mm ofspacing adjustment can be provided by different sizes of the bearingsupport component.

In some examples, the shim components 346C and 346D can include an entryramp 709, which can be similar to the entry ramp 614 described above andshown in FIG. 6B. A ratio R from a start of the ramp 709 to a beginningof a dovetail of each of the shim components 346C and 346D can be usedto maintain engagement of the dovetails during a shim insertionprocedure.

FIGS. 11, 12A, and 12B illustrate exploded views of a base component 344and a plate component 350 of a tibial prosthesis system 340 (FIG. 4A).The plate component 350 can correspond closely in size and shape with aresected proximal tibial surface. The plate component 350 can include asuperior surface 1102, an opposing bone contacting surface 1104, and aperipheral wall 1106 extending from the bone contacting surface 1104 tothe superior surface 1102. The peripheral wall 1106 can include a raisedperimeter, an anterior side 1108, a posterior side 1110, a medial side1112, and a lateral side 1114. The plate component 350 can include a PCLcut-out 1116 disposed at the posterior side 1110 to accommodate aposterior cruciate retaining ligament of a knee joint. While the platecomponent 350 is part of the provisional prosthesis system disclosedherein, it can also be part of a permanent prosthesis system or a sizingsystem.

The base component 344 can be secured to the plate component 350 bypositioning an inferior surface 476 of the base component 344 on thesuperior surface 1102 of the plate component 350. The base component 344can include at least one ramped surface 1122 extending between itsinferior surface 476 and its superior surface 352. The at least oneramped surface 1122 can be configured to engage one or more undercuts1120 of the plate component 350. A dovetail-like engagement, forexample, between the at least one ramped surface 1122 and the one ormore undercuts 1120 can act to inhibit medial/lateral movement betweenthe base 344 and plate 350 components. A perimeter undercut surroundingthe inferior surface 476 of the base component 344 can further mate withthe raised perimeter of the plate component 350 to inhibitanterior/posterior and medial/lateral movement between the base 344 andplate 350 components. To inhibit proximal/distal movement between thebase 344 and plate 350 components, a locking projection 1202 can extendfrom the inferior surface 476 of the base component 344 and can beconfigured to engage with a locking cavity 1204 extending inferiorlyfrom the superior surface 1102 of the plate component 350. As shown inFIG. 12B, the locking projection 1202 and the locking cavity 1204 canform an interference locking arrangement 1206.

FIGS. 13 and 14 illustrate perspective views of portions of a tibialprosthesis system 720, which can be similar to portions of the tibialprosthesis system 340, described above, and used in preparation forselecting a permanent tibial prosthesis system. FIG. 13 shows a bearingcomponent 722 and a base component 724. The base component 724 is alsoreferred to herein as a bearing support component. FIG. 14 shows thebearing component 722 and the base component 724, similar to FIG. 13, aswell as a spacer component 726 and a fastener 728. In an example, thetibial prosthesis system 720 can be used to mimic a total kneereplacement procedure in which a surgeon decides that aposterior-stabilized (PS) implant is suitable for a particular patient.One or more portions of the tibial prosthesis system 720 can be usedwith a permanent tibial prosthesis system such as, for example, a PSimplant. The fastener 728 can be used to “lock down” or secure thebearing component 722 to the base component 724. In an example, thefastener 728 can be a lockdown screw.

FIGS. 15A through 15D illustrate various perspective views of thebearing component 722 of FIGS. 13 and 14. FIG. 15A shows a superior orarticulating side of the bearing component 722. FIG. 15B shows a portionof the bearing component 722 cut along a midline in ananterior/posterior direction. FIG. 15C shows a portion of the bearingcomponent 722 cut along a midline in a medial/lateral direction. FIG.15D shows an inferior or underside of the bearing component 722.

The bearing component 722 can include a post 730 extending from anarticulating surface 732 and configured to engage with a femoralcomponent, and an aperture 734 configured to receive the fastener 728(see FIG. 14). The post 730 can include a pocket 736 extending from aninferior side 738 of the bearing component 722. The pocket 736 can haveone or more planar walls in its cross-section geometry (e.g.,trapezoidal cross-section geometry) to prevent or eliminate relativedisplacement between the bearing component 722 and the base component724. The inferior side 738 of the bearing component 722 can also includean opening 740 and a bottom portion 739 to receive one or both of thespacer component 726 (see FIG. 14) or a shim component, such as the shimcomponent described below and illustrated in FIGS. 17-20.

FIG. 16A illustrates a superior side 746 of the base component 724 andFIG. 16B illustrates an inferior side 748 of the base component 724. Thebase component 724 can include a platform 750 between medial and lateralcomponent portions. The platform 750 can include a post 752 configuredto align with the pocket 736 of the bearing component 722, and anaperture 754 configured to align with the aperture 734 of the bearingcomponent 722 and receive the fastener 728.

The base component 724 can be configured such that a plane of symmetryfor the post 752 is aligned with an axis of the opening 754. Theposition of the post 752 can help prevent an incorrect combination of aparticular bearing component 722 and a particular base component 724. Ifa particular bearing component 722 and a particular base component 724are not intended to be used together, relative positions of the bearingcomponent and the base component features can be offset and insertion ofa shim component can be prevented. This prevention can provide anindication of incompatibility. The base component 724 can include a rail756 extending around the platform 750 and configured to engage with ashim component.

FIG. 17 illustrates a perspective view of the spacer component 726,which is illustrated in FIG. 14. FIG. 18 illustrates a perspective viewof a shim component 758. In an example, the spacer component 726 can beavailable in a thinner size relative to the shim component 758. Thespacer 726 and the shim component 758 can provide a similar function ofproviding spacing between the bearing component 722 and the basecomponent 724, as similarly described above for shim component 346 (seeFIGS. 4A and 4B). In an example, the spacer component 726 can provide asubstantially similar spacing to a spacing provided between the bearingcomponent 722 and the base component 724 when the two components 722 and724 are assembled. The shim component 758 can be used in combinationwith or in lieu of the spacer component 726 to provide additional ortailored (e.g., differing medial/lateral or anterior/posterior) spacing,as described above and further described below. In an example, thespacer component 726 can be part of the tibial prosthesis system 720 asit is implanted in a knee joint. If additional or tailored spacing isneeded between the bearing component 722 and the base component 724, thespacer component 726 can optionally be removed and the shim component758 can be inserted.

As shown in FIG. 14, the spacer component 726 can be slidably insertedbetween the bearing component 722 and the base component 724. The spacercomponent 726 can include two extensions 760 and 762 configured toextend in an anterior/posterior direction when the spacer component 726is inserted between the bearing component 722 and the base component744. The extensions 760 and 762 can each engage with the inferior side738 of the bearing component and the superior side 746 of the basecomponent. Engagement between the extensions 760 and 762 and one or bothof the bearing component 722 and the base component 724 can include adovetail-like engagement. In an example, the extension 762 can includedovetail geometry 763 on an outer portion of the extension 762, whichcan be used to engage with dovetail geometry on the bearing component722. In an example, engagement between the extensions 760 and 762 andthe base component 724 can include rail geometry 765, which can matchand mate with the rail 756 on the base component 724. The spacercomponent 726 can include one or more handling alignment voids 764, orother coupling structures, to engage with an interface of a handlinginstrument, such as the handling instrument 354 (FIG. 6A).

The shim component 758 of FIG. 18 can similarly be slidably insertedbetween the bearing component 722 and the base component 724 and caninclude a first paddle 770, a second paddle 772, one or more handlingvoids 773, as well as a cutout feature 774 between the first 770 andsecond 772 paddles. The cutout feature 774 can be configured toaccommodate the lockdown screw 728. Similar to the extensions 760 and762 of the spacer component 726, portions of the shim component 758 canengage with one or both of the bearing component 722 and the basecomponent 744 can include a dovetail-like manner. In an example, theshim component 758 can include dovetail geometry 771, on a top surface,that mate with the bearing component 722 and rail geometry 773 that matewith the base component 724, on a bottom surface. In an example, one orboth of the first 770 and second 772 paddles can include an entry ramp776 and 778, respectively, on a top surface of the shim component 758.The entry ramps 776 and 778 can be similar to the entry ramp 709 shownin FIGS. 9 and 10.

The tibial prosthesis system 720 can be configured such that the spacercomponent 726 and the shim component 758 can both accommodate thelockdown screw 728 shown in FIG. 14. The lockdown screw 728 (FIG. 14)can be available in different sizes and a size of the screw can beselected based, in part, on a spacing between the bearing component 722and the base component 724. For example, if there is significant spacingbetween the bearing component 722 and the base component 724, a longerscrew can be used as compared to if there is less spacing between thebearing component and the base component 724.

The shim component 758 of FIG. 18 can be available in a plurality ofsizes. As described above in reference to the shim component 346, a setof different sized shim components 758 can be provided in a kit to allowfor varying levels of adjustment for the provisional tibial prosthesissystem 720. Moreover, the shim component 758 of FIG. 18 can be modifiedto have a height difference between the anterior and posterior edgesand/or the medial and lateral edges, as shown in FIGS. 8 and 10 inreference to the shim components 346B and 346D. Shim components having aheight difference between the anterior and posterior edges and/or themedial and lateral edges can be included in the kit of different-sizedshim components, which can also include different-sized shim componentshaving a uniform height.

The spacer component 726 and the shim component 768 can be used in bothleft and right tibial prosthesis systems and need not be side-specific.

FIG. 19 illustrates another example of a spacer component 780 that canbe used in combination with a tibial prosthesis system. The spacercomponent 780 can be used with the tibial prosthesis system 340 shown inFIG. 4B. In an example, the spacer component 780 can be used to provideless spacing compared to the shim component 346. Similar to the spacercomponent 726, the spacer component 780 can be used, in some examples,to provide approximately the same spacing provided between the basecomponent 344 and the bearing component 342. As similarly describedabove in reference to the spacer component 726, the spacer component 780can be part of the tibial prosthesis system 340 when it is implanted inthe knee. Although not visible due to its orientation in FIG. 19, thespacer component 780 can include one or more handling alignment voidsfor engaging with a handling instrument.

FIG. 20 illustrates an example of a spacer component 784 that can besimilar to the spacer component 726 of FIG. 17 and can also include anextension 786. A cutout feature 788 can be formed in the extension 786for accommodating a lockdown screw.

FIG. 21 illustrates the spacer component 784 in a tibial prosthesissystem 790, which can be similar to the tibial prosthesis system 720.The spacer component 784 can include the extension 786 and, togetherwith an anterior portion of a bearing component, can form a portion ofan aperture 792 configured to receive the fastener 728. In an example,the tibial prosthesis system 790 can be used for smaller sizeprostheses. As an overall size of the tibial prosthesis gets smaller,less material is available for clamping. The extension 786 can be usedto provide additional material for clamping when a lockdown screw ininserted through the tibial prosthesis system 790 and into the aperture792.

As described above in the method 500 of FIG. 5, after a provisionaltibial prosthesis has been implanted in a tibia of a patient, testingcan be performed to determine if proper knee joint kinematics arepresent. FIGS. 22-34 illustrate an example of a system for determiningforce balance on a knee joint during a surgical procedure, and thesystem can include full- or substantially full-surface sensing todetermine knee joint kinematics, including soft tissue balance of theknee joint. The system can include, among other things, a user interfacefor displaying the sensed data as a two- or three-dimensionalrepresentation of an area or volume of the prosthesis, such as anarticulation surface area of a tibial prosthesis. The various componentsof the system can be provided as a kit, as described below in referenceto FIG. 29.

FIG. 22 illustrates an example of a provisional or trial prosthesissystem 800 for use in a knee surgery to provide full- or substantiallyfull-surface sensing. The system 800 can be used in combination with auser interface for displaying sensing data. The trial prosthesis system800 can include one or more of a provisional femoral prosthesis 802, aprovisional tibial prosthesis system 804, and a handling instrument 806.The provisional tibial prosthesis system 804 can be similar to theprovisional tibial prosthesis systems described above, and can include abearing component 808, a shim component 810, a base component 812, and aplate component 814. The base component 812 and/or the plate component814 are also referred to herein as a bearing support component.

FIGS. 23A and 23B respectively illustrate assembled and component viewsof the bearing component 808. The bearing component 808 can be similarto the unitary bearing component 342 shown in FIG. 4B, or can include aplurality of components, such as a top portion 816, a frame 818, asensor plate 820, and a bottom portion 823. The sensor plate 820 caninclude one or both of a plurality of sensors 822 or a processor 824,which can be disposed on a top surface 826 of the sensor plate 820. Theframe 818 can include a plurality of apertures or openings 828 that canbe sized and/or shaped to correspond to the plurality of sensors 822 onthe sensor plate 820, thereby providing for precise force or pressuresensing. The top portion 816 of the bearing component 808 can include anarticulating side 830 and a non-articulating side 832. The bottomportion 823 of the bearing component can be configured to support thesensor plate 820 and can form a bottom non-articulating side 834 of thebearing component 808.

FIG. 24 illustrates the top surface 826 of the sensor plate 820,including the sensors 822 and the processor 824. In an example, thesensor plate 820 can include twenty-four sensors 822. In other examples,a configuration and quantity of the sensors 822, as well as the frame818, can be different than what is shown in FIG. 23B. The bearingcomponent 808 can be configured such that there are multiple sensors 822on the sensor plate 820 and the apertures 828 on the frame 818 cancorrespond to the sensors 822 in size, shape, or quantity.

The sensors 822 can include any suitable force or pressure sensors orreaders, such as, but not limited to, piezoelectric sensors, forcesensing resistors, force gauges, strain gauges, load cells,potentiometers, barometers, or the like. Example force sensors includeforce sensing resistor or capacitive flex circuits, piezoelectric film,piezoelectric elements, piezoresistive and piezoelectric polymers, metalfoil strain gages, semiconductor strain gages, piezoresistive andcapacitive pressure sensors, interferometric optical sensors, pathdisplacement optical sensors, optical fiber force sensors, and othersuitable sensing technologies.

The sensors 822 can occupy a substantial portion of the top surface 826of the sensor plate 820 such that the sensors align with a substantialportion of the superior articulating surface of the bearing component808, which can be an articulating side 830 of the top portion 816. Thesensor plate 820 can have a medial side M, a lateral side L, an anteriorside A, and a posterior side P, all of which can similarly apply toother components of the tibial prosthesis system 804. By configuring thesensors 822 to be generally spaced over a substantially portion of asurface that is parallel to, and aligned with, the articulating side 830of the top portion 816, the sensors 822 can facilitate precise sensingon both the medial M and lateral L sides and/or anterior A and posteriorP sides. Similarly, the sensors 822 can facilitate deep posteriorsensing, as represented by a medial posterior region 846 and a lateralposterior region 848 in FIG. 24. Posterior sensing can be beneficialwhen determining high-flex balance and roll-back, and/or to predictwear, for example. Data gathered from the sensors 822 is describedfurther below in reference to FIGS. 30-34.

FIG. 25 illustrates the frame 818 and the non-articulating side 832 (orunderside) of the top portion 816. The non-articulating side 832 of thetop portion 816 can include a plurality of projections 850, each ofwhich can be sized and shaped to fit within a corresponding aperture 828on the frame 818. Alternatively, the plurality of projections 850 can beseparate from, and positioned below, the top portion 816.

As described above, the apertures 828 on the frame can be configured tocorrespond and align with the sensors 822. Thus, in response to a forceon the articulating side 830 of the top portion 816, the projections 850can be configured to transfer a representative force to one or moresensors 822 aligned with such force. The articulating side 830 of thetop portion 816 can include inherent flexibility (e.g., via materialproperties or thickness) to allow applied forces to be appropriatelymeasured by the aligned sensors 822 and processed for one or more kneejoint balance determinations.

The isolated sensing compartments created by distinct projections 850and distinct apertures 828 of the frame 818 can ensure that only forcesapplied directly above a particular one or more sensors 822 aremeasured. The projections 850 can be formed of the same or a differentmaterial than other portions of the top portion 816, and such materialcan be any material used in surgical procedures and having sufficientstrength to sufficiently transfer force. In an example, the projections850, or a portion thereof, can be formed of metal.

In an example, the top portion 816 can be formed through injectionmolding, and the projections 850 can be inserted into cavities of thetop portion 816. The cavities of the top portion 816 can extend in aproximal-to-distal or distal-to-proximal direction and can correspond toa size and shape of the projections 850. Other designs can be used forthe top portion 816 and the projections 850 in addition to what is shownin FIG. 25. By way of example, the articulating side 830 can be formedfrom a separate piece attachable to one or more other components used toform the top portion 816. In an example, the projections 850 can occupya larger depth of the top portion 816, defined as a distance between thearticulating side 830 and the non-articulating side 832. Once in place,the projections 850 can extend through a bottom of the top portion 816.

FIGS. 26A through 27C illustrate different components of the provisionaltibial prosthesis system 804 in use with a handling instrument 806 shownin FIG. 22. This use can be similar to the shim handling instrument 354shown in FIG. 6A and used with the provisional tibial prosthesis system340. FIG. 26A shows the plate component 814 of the tibial prosthesissystem 804 attached to the handling instrument 806. In an example, theplate component 814 can be attached to the handling instrument 806 usinga handling alignment void 852 in an anterior portion of the platecomponent 814. FIG. 26B shows the bearing component 808 attached to thehandling instrument 806 using a handling alignment void 854 formed in ananterior portion of the bearing component 808. The handling instrument806 can be configured to releasably secure various components of thetibial prosthesis system 804, as further shown in FIG. 27A. In anexample, the handling instrument 806 can be configured to engage withone handling void in the component it secures. In other examples, thehandling instrument 806 can be configured to engage with two handlingvoids in the component it secures.

In an example, the bearing component 808, the base component 812, andthe plate component 814 can be assembled together in preparation forimplanting the tibial prosthesis system 804 on a tibia, and the handlinginstrument 806 can be attached to the plate component 814, as shown inFIG. 22. The shim component 810 can be included within the tibialprosthesis system 814, as shown in FIG. 22, when the other componentsare implanted, or the shim component 810 can be implanted in a laterstep.

FIG. 27A illustrates the shim component 810 attached to the handlinginstrument 806 with a handling alignment void 856, and prior toinserting the shim component 810 between the bearing component 808 andthe base component 812. In an example, the shim component 810 can have athickness T1. FIG. 27B illustrates additional shim components 858, 860,862 and 864 of increasing thicknesses (in a proximal to distaldirection). A thickness T2 of the shim component 858 can be greater thanthe thickness T1 of the shim component 810. Similarly, a thickness T3 ofthe shim component 860 can be greater than the thickness T2 of the shimcomponent 858. In an example, the shim components 810, 858, 860, 862 and864 can have a thickness range between 10 mm and 14 mm, inclusive.

As described above in reference to the tibial prosthesis system 340, aparticular shim component can be selected for insertion based on adistance between the bearing component 808 and the base component 812implanted on a tibia. Also, as described above in reference to themethod 500 of FIG. 5, a chosen shim component, selected from the shimcomponents 810, 858, 860, 862 and 864, can be inserted and then testingcan be performed to determine if a different shim component should beselected to replace an initially selected shim component. In an example,testing can be performed to analyze a force or pressure balance on atleast a portion of the knee joint using the sensors 822 of the bearingcomponent 808. If the force or pressure data collected is notsatisfactory, a different shim component can be inserted. These stepscan be repeated until satisfactory force or pressure data is observed.Optionally, in conjunction with or in lieu of shim selection, a surgeoncan adjust ligament balance through ligament release if testing balancedata is not satisfactory. The bearing component 808, which includes thesensors 822 and the frame 818, can be configured for providing acomprehensive set of sensing data about a force balance on a knee joint.

FIG. 27C illustrates a shim component 866 having a thickness T6. In anexample, the thickness T6 of the shim component 866 can be less than thethickness T1 of the shim component 810. In an example, the thickness T6of the shim component 866 can be about 6 mm. In other examples, thethickness T6 can be less than or greater than 6 mm. In an example, theshim component 866 can be used in combination with one of the shimcomponents 810, 858, 860, 862 and 864 to provide additional spacingbetween the bearing component 808 and the base component 812. As shownin FIG. 27C, the shim component 866 can include an aperture 868 forengaging with the handling instrument 806 and can be configured forinsertion between a shim component and the bearing component 808.

The components of the trial prosthesis system 800 can be available invarying sizes to accommodate different size knee joints. In an example,a surgeon or other caregiver can determine an approximate suitable sizeor shape of the trial prosthesis system 800 using a template. FIG. 28illustrates a plurality of templates 880 that can be sized and/or shapedfor use in determining a proper tibial tray size prior to selecting asuitable size or shape of the tibial prosthesis system 804. Thetemplates 880 can range in size from a smallest size A to a largest sizeF, as shown.

FIG. 29 illustrates an example of a kit 900 that can include a userinterface 902, a handling instrument 904, and a plurality of components906 that can include some or all of the components described above forthe trial prosthesis system 800, or related variants of such componentsalso described above. The user interface can be configured to beconnected to the sensors 822 and the processor 824 of the bearingcomponent 808 of the tibial prosthesis system 804. The user interface902 can include a computing device configured to process data from thesensors 822 or the processor 824, compare such data to a historicaldatabase, and display one or more balance determinations on a screen ofthe user interface. The user interface 902 can be configured to be smalland portable, as well as wireless, such that the user interface 902 canbe used in an area, or surrounding area, of a surgical procedure. Insome examples, the user interface 902 can be connected to anotherdisplay device such as, for example, a computer or TV monitor in thearea of the surgical procedure.

In an example, the kit 900 can include all components for the trialprosthesis system 800, including the provisional femoral prosthesis 802and a plurality of shim components, as described above in reference toFIG. 27B. In an example, the kit 900 can include at least one shimcomponent having a height difference between the anterior and posterioredges and/or the medial and lateral edges. The kit 900 can be designedsuch that the user can have some or all of the components for the kneeprocedure located together. The components of the kit 900 can be housedinside a tray 907 that, together with one or more of the components thatit houses, can be disposable after a single use. In an example, the kit900 can include some of the components of the trial prosthesis system800 and some of the other components can be provided separately duringthe surgical procedure.

FIG. 30 illustrates an example of a digital image 908 that can begenerated and displayed on the user interface 902. As described above,the bearing component 808 of the tibial prosthesis system 804 caninclude the sensor plate 820 having the plurality of sensors 822. In anexample, the sensor plate 820 can have a twenty-four sensorconfiguration. The sensor plate 820 can include the processor 824, whichcan be configured to receive and process data from the plurality ofsensors 822 before communicating the data to the user interface 902. Theprocessor 824 can alternatively be integrated with the computing deviceof the user interface 902. The user interface 902 can have a wired orwireless connection with the sensor plate 820. The wired or wirelessconnection can utilize any type of network, such as the Internet, atelephone network, a cable network, or a wireless network.

The digital image 908 can be a two-dimensional (shown), or optionallythree-dimensional, representation of the area of the tibial prosthesis800 that is aligned with the sensors 822. The data from the sensors 822can be mapped into a multi-point data registry. In an example, a24-point data registry is mapped based on having twenty-four sensors822. In other examples, the data registry can have more or less thantwenty-four points based on having more or less than twenty-four sensors822 on the sensor plate 820. As described above, a configuration anddesign of the bearing component 808, including the frame 818 having theopenings 828 aligned with the sensors 822, can allow for independentsensing areas that can be noticeably mapped and presented on the userinterface 902.

FIG. 31 illustrates an example of a digital image 910 that can bedisplayed on the user interface 902. The digital image 912 can show aforce value generated by each of the sensors 822 on the sensor plate820. The force value generated can be the result of force transmitted bythe projections 850 of the top portion 816, or alternatively, columnsextending between the top portion 816 and the bottom portion 823, whichinteract with the sensors 822. Based on the data shown in the digitalimage 912, the computing device of the user interface 902 can generatean image 914, which can include a collective force in each of two halvesor four quadrants on the provisional tibial prosthesis system 804. Theimage 914 can include indicators representing medial M, lateral L,anterior A, and posterior P sides, or combinations thereof, of theprovisional tibial prosthesis system. An image 916 showingmedial-lateral and anterior-posterior center of force data can also begenerated by the user interface 902.

FIG. 32 illustrates an example of another digital image 918 that can bedisplayed on the user interface 902. The surgeon or other user canselect a particular zone, which can be conceptualized as a green or safezone, representing acceptable force limits in flexion and/or extension.In flexion, the green zone can be represented by limit points 920 and922, for example, and in extension, the green zone can be represented bylimit points 924 and 926, for example. Optionally, the green zone can beestablished based, at least in part, on statistically relevanthistorical data from one or more patient trials. For example, upon thecollection of a number of trials of empirical data, data may bestatistically analyzed (either by the analysis program, or anotherexternal program) to form suggested pre-determined pressure criteria,i.e., upper and lower limits, to aid the surgeon in recognizingpotential elevated pressure readings. The suggested pre-determinedpressure criteria can define statistically sound thresholds andallowable limits under certain conditions, and can be constantlyadjusted as more information becomes available in the database.

Forces values generated by, and acquired from, the sensors 822 can thenbe mapped and shown in image 928 of FIG. 33, for example. The image 928can indicate forces or force zones (e.g., medial zone, lateral zone,anterior zone, posterior zone, medial/anterior zone, medial/posteriorzone, lateral/anterior zone, or lateral/posterior zone) that are toohigh (labeled as 930) relative to the green zone, within the acceptablegreen zone (labeled as 931), and that are too low (labeled as 932)relative to the green zone. The computing device of the user interfacecan be configured to compare the acquired force data to green zone data,the latter of which can be stored in software on the user interface'shard drive. FIG. 34 illustrates the user interface 902 with multipleimages based on the green zone selected by the surgeon. One or moreimages can be used by the surgeon, for example, to correct excessiveforces or force zones.

In other examples, additional or alternative data can be displayed toguide the surgeon. The numbers presented as force values in FIGS. 31-34are exemplary to show the type of data that can be generated anddisplayed for use by the surgeon. The particular numbers represented arenot intended to be limiting, but rather, an example for determiningbalance or imbalance of the knee joint. The force numbers generated bythe sensors and mapped into the data point registry can be compared topreviously gathered numbers over time that can be indicative of adequateto inadequate balance and alignment.

In an example, as described above, the user interface 902 can beconfigured to include a computing device and the user interface 902 canbe provided as part of the kit 900. In other examples, the sensors 822and the processor 824 can be connected to any other type of computingdevice to generate the types of data described above, based on the datafrom the sensors 822.

Closing Notes:

Existing provisional systems, kits, and methods fail to provide asurgeon with insight of knee joint kinematics if an angled bone cut(e.g., a bone cut that is not parallel to a joint line of a knee) ismade to a distal end of a femur or a proximal end of a tibia. Existingprovisional systems, kits, and methods further require the stacking of arelatively high number of provisional components to arrive at anappropriate configuration of a permanent tibial prosthesis system orfail to provide sensed force or pressure data providing a real-timeindication of provisional knee joint balance. Advantageously, thepresent provisional systems, kits, and methods can include a shimcomponent, having one or both of a medial edge height that is differentthan a lateral edge height or an anterior edge height that is differentthan a posterior edge height, or a sensor coupled to or integrated witha bearing component, a bearing support component, or the shim component.Such a shim component configuration can provide the surgeon with kneejoint kinematic insight regarding an angled bone cut to the femur ortibia before the cut is made and can reduce the number of provisionalcomponents needed during surgery sizing. The sensor can facilitatereal-time knee joint balancing testing.

The above Detailed Description includes references to the accompanyingdrawings, which form a part of the Detailed Description. The drawingsshow, by way of illustration, specific embodiments in which the presenttibial prosthesis systems, kits, and methods can be practiced. Theseembodiments are also referred to herein as “examples.” While certainexamples are shown and described with respect to a left knee or a rightknee, it is to be appreciated that the present disclosure is equallyapplicable to both the left and right knees. All examples can also beused in partial or total knee replacement procedures.

The above Detailed Description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreelements thereof) can be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. Also, various features or elementscan be grouped together to streamline the disclosure. This should not beinterpreted as intending that an unclaimed disclosed feature isessential to any claim. Rather, inventive subject matter can lie in lessthan all features of a particular disclosed embodiment. Thus, thefollowing claims are hereby incorporated into the Detailed Description,with each claim standing on its own as a separate embodiment. The scopeof the invention should be determined with reference to the appendedclaims, along with the full scope of equivalents to which such claimsare entitled.

In the event of inconsistent usages between this document and anydocument so incorporated by reference, the usage in this documentcontrols.

In this document, the terms “a” or “an” are used to include one or morethan one, independent of any other instances or usages of “at least one”or “one or more.” In this document, the term “or” is used to refer to anonexclusive or, such that “A or B” includes “A but not B,” “B but notA,” and “A and B,” unless otherwise indicated. In this document,“anterior” refers to a direction generally toward the front of apatient, “posterior” refers to a direction generally toward the back ofthe patient, “medial” refers to a direction generally toward the middleof the patient, and “lateral” refers to a direction generally toward theside of the patient. In this document, the phrase “anterior/posteriordirection” is used to include an anterior to posterior direction or aposterior to anterior direction.

In the appended claims, the terms “including” and “in which” are used asthe plain-English equivalents of the respective terms “comprising” and“wherein.” The terms “including” and “comprising” are open-ended, thatis, a system, kit, or method that includes elements in addition to thoselisted after such a term in a claim are still deemed to fall within thescope of that claim. Also, in the following claims, the “kit” claims areintended to provide protection for, among other things, a set novel shimcomponents, at least one of which includes differing heights, andsensor, bearing support, and handling instrument components having afunctional relationship with the novel shim components. Moreover, in thefollowing claims, the terms “first,” “second,” and “third,” etc. areused merely as labels, and are not intended to impose numericalrequirements on their objects.

The Abstract is provided to allow the reader to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims.

What is claimed is:
 1. A tibial prosthesis system, comprising: a bearingcomponent having a superior articulating surface and an inferiorsurface, the inferior surface having a base component engagementfeature; a base component having a superior surface and an inferiorsurface, the superior surface having a bearing component engagementfeature configured to mate with the base component engagement featuresuch that the bearing component and the base component are removablyengageable with each other, whereby mating of the base componentengagement feature and the bearing component engagement featurerestrains at least one of anterior/posterior movement or medial/lateralmovement between the bearing component and the base component; and ashim component configured to be slidable between the inferior surface ofthe bearing component and the superior surface of the base component,when the bearing component and the base component are engaged with eachother, to removably engage the shim component with at least one of thebearing component and the base component, the shim component includingone or both of a medial edge having a different height than a lateraledge or an anterior edge having a different height than a posterioredge, wherein the shim component is sized and shaped to allow passage ofthe base component engagement feature or the bearing componentengagement feature such that the base component engagement feature andthe bearing component engagement feature remain mated together when thebearing component and the base component are engaged with each other andthe shim component is slid therebetweeen.
 2. The tibial prosthesissystem of claim 1, wherein an inferior surface of the shim componentincludes a medial to lateral angle of between +3 degrees and −3 degrees,inclusive, or an anterior to posterior angle of between +3 degrees and−3 degrees, inclusive.
 3. The tibial prosthesis system of claim 1,wherein the inferior surface of the bearing component includes a slot,and a superior surface of the shim component includes a rail configuredto slidably engage the slot.
 4. The tibial prosthesis system of claim 1,wherein the base component includes a first component, having a superiorsurface and an inferior surface, and a second component configured toreceive and engage the inferior surface of the first component.
 5. Thetibial prosthesis system of claim 4, wherein the first componentincludes at least one ramped surface extending between its inferiorsurface and superior surface, the at least one ramped surface configuredto engage an undercut of the second component, and wherein a projectionextending from the inferior surface of the first component is configuredto engage with a cavity of the second component.
 6. The tibialprosthesis system of claim 4, wherein the second component is one of asizing plate component, a provisional plate component, or a permanentplate component.
 7. The tibial prosthesis system of claim 1, wherein thedifferent height of the medial and lateral edges or of the anterior andposterior edges is measured in a proximal/distal direction.
 8. Thetibial prosthesis system of claim 1, wherein the shim component isconfigured to secure a position of the bearing component and the basecomponent relative to each other.
 9. The tibial prosthesis system ofclaim 1, wherein the bearing component engagement feature of the basecomponent includes a projection and the base component engagementfeature of the bearing component includes a cavity, the projectionconfigured to at least partially engage within the cavity.
 10. Thetibial prosthesis system of claim 9, wherein the engagement of theprojection of the base component at least partially within the cavity ofthe bearing component is configured to inhibit at least one of relativeanterior/posterior movement or relative medial/lateral movement betweenthe base and bearing components.
 11. The tibial prosthesis system ofclaim 1, further comprising: one or more sensors coupled to orintegrated with at least one of the bearing component, the basecomponent, or the shim component.
 12. The tibial prosthesis system ofclaim 11, wherein the one or more sensors include a plurality of sensorscoupled to or integrated with the bearing component.
 13. The tibialprosthesis system of claim 12, wherein the plurality of sensors arepositioned between the superior articulating surface and the inferiorsurface of the bearing component.
 14. The tibial prosthesis system ofclaim 1, wherein the shim component can be removed from engagement withthe at least one of the bearing component and the base component, whenthe bearing component and the base component are engaged with eachother, without disengaging the base component and bearing component fromone another.
 15. A tibial prosthesis system, comprising: a provisionalbearing component having a base component engagement feature; aprovisional base component having a bearing component engagement featureconfigured to mate with the base component engagement feature such thatthe provisional bearing component and the provisional base component canbe removably engaged with each other, whereby mating of the basecomponent engagement feature and the bearing component engagementfeature restrains at least one of anterior/posterior movement ormedial/lateral movement between the provisional bearing component andthe provisional base component; and a set of different sized shimcomponents, at least one of the shim components including one or both ofa medial edge having a different height than a lateral edge or ananterior edge having a different height than a posterior edge, whereineach shim component is configured to be insertable between theprovisional bearing component and the provisional base component toremovably engage the shim component with at least one of the provisionalbearing component and the provisional base component, whereby the shimcomponent does not disturb the mating of the base component engagementfeature and the bearing component engagement feature when theprovisional bearing component and the provisional base component areengaged with each other and the shim component is inserted therebetweensuch that the provisional bearing component and the provisional basecomponent retain engagement with each other when the shim component isinserted therebetween.
 16. The tibial prosthesis system of claim 15,wherein an inferior surface of at least one shim component, from the setof different sized shim components, includes a medial to lateral angleof between +3 degrees and −3 degrees, inclusive, or an anterior toposterior angle of between +3 degrees and −3 degrees.
 17. The tibialprosthesis system of claim 15, further comprising: instructions forinserting at least one shim component, from the set of different sizedshim components, between the provisional bearing component and theprovisional base component.
 18. The tibial prosthesis system of claim17, wherein each shim component provides a spacing between theprovisional bearing component and the provisional base component in arange between 10 mm and 20 mm, inclusive.
 19. The tibial prosthesissystem of claim 15, further comprising: one or more sensors integratedwith the shim component.
 20. The tibial prosthesis system of claim 15,further comprising: a set of different sized base components.
 21. Thetibial prosthesis system of claim 15, further comprising: a shimhandling instrument including an interface configured to engage with afront end portion of each of the set of different sized shim components.22. The tibial prosthesis system of claim 21, wherein the shim handlinginstrument is used for insertion and removal of each shim componentbetween the provisional bearing component and the provisional basecomponent, when the bearing component and the base component are engagedwith each other, without disengaging the provisional base component andthe provisional bearing component from one another.
 23. A tibialprosthesis system, comprising: a bearing component having a superiorarticulating surface and an inferior surface, the inferior surfacehaving a base component engagement feature; a base component having asuperior surface and an inferior surface the superior surface having abearing component engagement feature configured to mate with the basecomponent engagement feature such that the bearing component and thebase component can be removably coupled to each other; one or more shimcomponents configured to be slidable between the inferior surface of thebearing component and the superior surface of the base component toremovably engage at least one of the bearing component and the basecomponent, at least one of the one or more shim components including oneor both of a medial edge having a different height than a lateral edgeor an anterior edge having a different height than a posterior edge,wherein the one or more shim components do not disrupt the mating of thebase component engagement feature and the bearing component engagementfeature when the provisional bearing component and the provisional basecomponent are coupled to each other and the one or more shim componentsis slid therebetween, whereby the coupling of the bearing component andthe base component is not disturbed when the one or more shim componentsis slid therebetween.
 24. The tibial prosthesis system of claim 23,wherein the one or more shim components include a first shim and asecond shim.
 25. The tibial prosthesis system of claim 23, wherein thebearing component includes a post extending from the superiorarticulating surface.
 26. The tibial prosthesis system of claim 23,further comprising: a screw configured to extend partially through eachof the bearing component and the base component, in a distal directionfrom the superior articulating surface, to attach the bearing componentto the base component.
 27. The tibial prosthesis system of claim 26,wherein the one or more shim components are configured to be slidablebetween the inferior surface of the bearing component and the superiorsurface of the base component when the screw attaches the bearingcomponent to the base component.
 28. The tibial prosthesis system ofclaim 26, wherein the spacer component is removable from the tibialprosthesis system prior to sliding the one or more shim componentsbetween the inferior surface of the bearing component and the superiorsurface of the base component.
 29. The tibial prosthesis system of claim23, wherein each of the one or more shim components can be removed fromengagement with the at least one of the bearing component and the basecomponent, when the bearing component and the base component are engagedwith each other, without disengaging the base component and the bearingcomponent from one another.
 30. The tibial prosthesis system of claim23, further comprising a spacer component configured to be insertedbetween the inferior surface of the bearing component and the superiorsurface of the base component to removably engage at least one of thebearing component and the base component in the absence of the one ormore shim components therebetween.
 31. A tibial prosthesis system,comprising: a bearing component having a base component engagementfeature; a base component having a bearing component engagement feature,whereby the base component engagement feature and the bearing componentengagement feature are configured to mate with each other to removablycouple the bearing component with the base component, and whereby matingof the base component engagement feature with the bearing componentengagement feature restrains at least one of anterior/posterior movementor medial/lateral movement between the bearing component and the basecomponent; and a shim component configured to be inserted between thebearing component and the base component, the shim component includingone or both of a medial edge having a different height than a lateraledge or an anterior edge having a different height than a posterioredge, whereby the shim component provides spacing between the bearingcomponent and the base component when the shim component is insertedtherebetween, whereby the shim component is removably engageable with atleast one of the bearing component and the base component, whereby theshim component includes a posterior recess that allows the basecomponent engagement feature and the bearing component engagementfeature to remain mated together when the bearing component and the basecomponent are coupled to each other and the shim component is insertedtherebetween, and whereby the shim component does not disturb couplingof the bearing component and the base component when the shim componentis inserted therebetween.
 32. A tibial prosthesis system, comprising: abearing having a superior surface and an inferior surface, the inferiorsurface having a base engagement feature; a base having a superiorsurface and an inferior surface, the superior surface having a bearingengagement feature, whereby the bearing and the base can be removablycoupled to each other through mating of the bearing engagement featurewith the base engagement feature, and whereby mating of the baseengagement feature with the bearing engagement feature restrains atleast one of anterior/posterior movement or medial/lateral movementbetween the bearing and the base; and a shim including one or both of amedial edge having a different height than a lateral edge or an anterioredge having a different height than a posterior edge, the shim having atleast one mating feature configured for engagement with a shim matingfeature on at least one of the bearing and the base, whereby the shim isslidable between the bearing and the base, when the bearing and the baseare coupled to each other, to removably engage the at least one matingfeature on the shim with the shim mating feature on the at least one ofthe bearing and the base, whereby the shim provides spacing between thebearing and the base, and whereby the shim does not disturb the couplingof the bearing engagement feature and the base engagement feature, andwhereby the bearing and the base remain coupled to each other when theshim is slid therebetween.